If you do that, it expands your test matrix quadratically.

So, it makes sense if you have infinite testing budgets.

Personally, I prefer exhaustively testing the upgrade path, and investing in reducing the time it takes to push out a hot fix. Chicken bits are also good.

I haven’t heard of any real world situations where supporting downgrades of persistent formats led to best of class product stability.

Would love to hear of an example.